9-Nitrocamptothecin inhibits tumor recrosis factor-mediated activation of human immunodeficiency virus type 1 and enhances apoptosis in a latently infected T cell clone.
Transition from latency to active replication is a crucial stage for the process of human immunodeficiency virus type 1 (HIV-1) infection and life cycle. HIV-1 replication in latently infected cells can be strongly induced by the cytokine tumor necrosis factor alpha (TNF-alpha) and the proliferation-arresting chemical sodium butyrate (NaB). We have investigated the ability of the drug 9-nitrocamptothecin (9NC), a potent cellular topoisomerase I (topo I) inhibitor currently in clinical trials in cancer patients, to regulate HIV-1 replication in latently infected lymphocytic ACH-2 cells on reactivation with either TNF-alpha or NaB. Treatment of ACH-2 cells with 9NC alone resulted in increased levels of viral transcripts, while there was a slight reduction or no change in the levels of host cell transcripts. However, pretreatment of ACH-2 cells with 9NC inhibited TNF-alpha-induced extracellular HIV-1 p24 levels up to approximately 95% and nearly 80% of the cell-associated viral RNAs. The quantitative decrease in viral products was concomitant with a decrease in cellular gene expression and induction of apoptosis in the host cells. 9NC blocked the infected cells at the boundary of the S and G2 phases, resulting in an accelerated apoptosis that was further enhanced with TNF-alpha treatment. Similar results were observed following concurrent exposure to TNF-alpha and 9NC, but 9NC failed to inhibit upregulation of HIV-1 mRNA in ACH-2 cells exposed to TNF-alpha before 9NC treatment. Further, 9NC had no inhibitory effect on NaB-induced apoptosis and upregulation of HIV-1 mRNA expression regardless of whether 9NC and NaB were used concurrently or in various treatment sequences. In uninfected lymphocytic CEM cells derived from a common parental cell line, a slight downregulation of cellular gene expression was detected along with low-level apoptosis. These results demonstrate that 9NC impairs TNF-alpha-induced, but not NaB-induced, HIV-1 activation, and suggest a means of inhibiting active HIV-1 viremia arising as a result of elevated TNF-alpha levels.
Moulton
S
S
Division of Transfusion Transmitted Diseases, CBER/Food and Drug Administration, Rockville, Maryland 20852-1448, USA.
Pantazis
P
P
Epstein
J S
JS
Sadaie
M R
MR
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects; D015658:HIV Infections / Q000473:pathology; D015497:HIV-1 / Q000187:drug effects* / Q000254:growth & development; D006801:Humans; D012333:RNA, Messenger / Q000187:drug effects; D012367:RNA, Viral / Q000378:metabolism; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects* / Q000821:virology; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D015854:Up-Regulation; D014775:Virus Activation
D000970:Antineoplastic Agents; D012333:RNA, Messenger; D012367:RNA, Viral; D014409:Tumor Necrosis Factor-alpha; C079905:rubitecan; D002166:Camptothecin